Antenna apparatus

Abstract

An antenna apparatus includes: an antenna array that: i) includes a plurality of antennas arranged next to each other in a predetermined direction, ii) is supplied with power from a power source, and iii) transmits radio waves; and a plurality of dummy antennas that: i) are provided on opposite sides of the antenna array in the predetermined direction, ii) are supplied with power from an electric field leaked from the antennas of the antenna array, and iii) transmit radio waves. Thus, it is possible to prevent an accuracy of detecting a target from deteriorating.

What is claimed is: 
     
       1. An antenna apparatus comprising:
 an antenna array that: i) includes a plurality of antennas arranged next to each other in a predetermined direction, ii) is supplied with power from a power source, and iii) transmits radio waves; 
 a plurality of dummy antennas that: i) are provided on opposite sides of the antenna array in the predetermined direction, ii) are supplied with power from an electric field leaked from the antennas of the antenna array, and iii) transmit radio waves; and 
 a plurality of matching elements each of which is connected to an end of each of the plurality of dummy antennas. 
 
     
     
       2. The antenna apparatus according to  claim 1 , wherein
 an impedance value of each of the matching elements is substantially identical to a load impedance value of each of the antennas of the antenna array. 
 
     
     
       3. The antenna apparatus according to  claim 1 , wherein
 a direction of polarized waves in radiation patterns transmitted from the matching elements is substantially orthogonal to a direction of polarized waves in radiation patterns transmitted from the antennas of the antenna array. 
 
     
     
       4. The antenna apparatus according to  claim 1 , wherein
 a shape of the dummy antennas is substantially identical to a shape of the antennas of the antenna array. 
 
     
     
       5. The antenna apparatus according to  claim 1 , wherein
 a distance between one of the antennas of the antenna array and one of the dummy antennas is substantially identical to an arrangement distance between adjacent ones of the antennas of the antenna array, the one antenna being provided at an end of the antenna array, and the one dummy antenna being provided adjacent to the one antenna provided at the end of the antenna array. 
 
     
     
       6. The antenna apparatus according to  claim 1 , wherein
 one end of each of the dummy antennas is unconnected. 
 
     
     
       7. The antenna apparatus according to  claim 1 , wherein
 one end of each of the dummy antennas is shorted. 
 
     
     
       8. The antenna apparatus according to  claim 1 , wherein
 a shape of the dummy antennas is different from a shape of the antennas of the antenna array. 
 
     
     
       9. The antenna apparatus according to  claim 1 , wherein
 a distance between one of the antennas of the antenna array and one of the dummy antennas is different from an arrangement distance between adjacent ones of the antennas of the antenna array, the one antenna being provided at an end of the antenna array, and the one dummy antenna being provided adjacent to the one antenna provided at the end of the antenna array. 
 
     
     
       10. The antenna apparatus according to  claim 1 , wherein
 each of the matching elements is formed in a substantially rectangular shape having a concavity on one side, and 
 the concavity is connected to a conductor line. 
 
     
     
       11. The antenna apparatus according to  claim 1 , wherein
 the matching elements are provided in a direction that is different from a direction in which the antennas of the antenna array are provided relative to the dummy antennas. 
 
     
     
       12. The antenna apparatus according to  claim 1 , wherein
 each of the dummy antennas includes a plurality of patch elements, 
 the patch elements are connected to one another by a conductor line, and 
 one of the patch elements is connected to one of the matching elements by the conductor line. 
 
     
     
       13. The antenna apparatus according to  claim 12 , wherein
 the conductor line connecting the one patch element to the one matching element is substantially L-shaped. 
 
     
     
       14. The antenna apparatus according to  claim 12 , wherein
 the patch elements are provided axisymmetrically. 
 
     
     
       15. The antenna apparatus according to  claim 12 , wherein
 a first half of the patch elements have widths that decrease as the patch elements are provided closer to the matching element, and 
 a second half of the patch elements have widths that increase as the patch elements are provided closer to the matching element. 
 
     
     
       16. The antenna apparatus according to  claim 12 , wherein
 lengths of the patch elements are substantially identical to each other.